Population Genetics of Freshwater Mollusks and Gastropods

Freshwater mollusks and gastropods constitute a diverse assemblage that underpins aquatic ecosystems worldwide, providing vital services such as biofiltration, nutrient cycling and substrate stabilisation. Many species are imperilled by habitat fragmentation, pollution, invasive species and changes to hydrological regimes. Population genetics offers tools to characterise levels of genetic diversity, detect population structure and infer demographic history, thereby informing conservation and management. Traditional markers such as mitochondrial DNA and microsatellites have revealed patterns of high gene flow in widespread snails and marked differentiation in isolated mussel populations. More recently, genome-wide approaches—particularly reduced-representation sequencing—have enabled fine-scale resolution of cryptic lineages, estimation of effective population size and identification of barriers to dispersal. Insights into host-mediated larval transport, lifespan-dependent genetic responses and the role of passive versus active dispersal strategies have refined our understanding of connectivity in riverine networks. Ultimately, integrative population genetic studies guide the delineation of management units, captive breeding efforts and habitat restoration to safeguard freshwater mollusk and gastropod diversity.

Research from Nature Portfolio

Genome-wide single nucleotide polymorphism data generated by a double-digest restriction-site associated DNA sequencing approach have redefined species boundaries in the North American freshwater mussel genus Cyprogenia. Analyses identified three evolutionarily significant lineages—each corresponding to distinct highland regions—with further subdivision at the level of individual river systems. Bayesian species delimitation supported recognition of three species rather than two, and comparisons of destructive and non-destructive sampling protocols demonstrated that trace samples yield comparable SNP quality. These findings inform the design of precise conservation units and underpin evidence-based restoration strategies for urgently threatened mussels.

Population Genetics of Freshwater Mollusks and Gastropods publication trend

The graph below shows the total number of articles in population genetics of freshwater mollusks and gastropods across all publications each year (not limited to Nature Index journals).

Technical terms

Effective population size (Ne): The size of an idealised population that would experience genetic drift at the same rate as the observed population.

Gene flow: The movement of genes between populations through dispersal or migration, which counteracts differentiation.

Genetic drift: Random changes in allele frequencies within a population, particularly pronounced in small populations.

Single Nucleotide Polymorphism (SNP): A variation at a single nucleotide position in the genome among individuals of a species.

Microsatellite DNA: Short tandem repeats of DNA used as highly polymorphic markers for assessing genetic diversity and structure.

ddRAD-Seq: A reduced-representation sequencing method that produces genome-wide SNP data for population genomic inference.

Phylogenomics: The study of evolutionary relationships using genome-scale data to reconstruct species histories and delimit taxa.

References

1. Genome-wide SNPs redefines species boundaries and conservation units in the freshwater mussel genus Cyprogenia of North America. Scientific Reports (2021).
2. Establishing conservation units to promote recovery of two threatened freshwater mussel species (Bivalvia: Unionida: Potamilus). Ecology and Evolution (2021).
3. Inbreeding does not alter the response to an experimental heat wave in a freshwater snail. PLOS ONE (2019).
4. High levels of multiple paternity in a spermcast mating freshwater mussel. Ecology and Evolution (2018).